adv7344 Analog Devices, Inc., adv7344 Datasheet - Page 66

• Manufacturer Part Number: adv7344
• Description: Multiformat Video Encoder Six 14-bit Noise Shaped Video Dacs
• Manufacturer: Analog Devices, Inc.

ADV7344
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0
1M
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1
GROUP DELAY (Seconds)
GROUP DELAY (Seconds)
Figure 87. Output Filter Plot for SD, 16× Oversampling
Figure 89. Output Filter Plot for HD, 4× Oversampling
Figure 88. Output Filter Plot for ED, 8× Oversampling
GROUP DELAY (Seconds)
CIRCUIT FREQUENCY RESPONSE
CIRCUIT FREQUENCY RESPONSE
CIRCUIT FREQUENCY RESPONSE
10M
10M
FREQUENCY (Hz)
FREQUENCY (MHz)
FREQUENCY (Hz)
10
MAGNITUDE (dB)
100M
100M
MAGNITUDE (dB)
MAGNITUDE (dB)
PHASE (Degrees)
100
(Degrees)
PHASE
(Degrees)
PHASE
1G
1G
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160
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Rev. 0 | Page 66 of 88
PRINTED CIRCUIT BOARD (PCB) LAYOUT
The ADV7344 is a highly integrated circuit containing both
precision analog and high speed digital circuitry. It has been
designed to minimize interference effects on the integrity of the
analog circuitry by the high speed digital circuitry. It is
imperative that these same design and layout techniques be
applied to the system-level design so that optimal performance
is achieved.
The layout should be optimized for lowest noise on the
ADV7344 power and ground planes by shielding the digital
inputs and providing good power supply decoupling.
It is recommended to use a 4-layer printed circuit board with
ground and power planes separating the signal trace layer and
the solder side layer.
Component Placement
Component placement should be carefully considered to
separate noisy circuits, such as clock signals and high speed
digital circuitry from analog circuitry.
The external loop filter components and components connected
to the COMP, V
possible to and on the same side of the PCB as the ADV7344.
Adding vias to the PCB to get the components closer to the
ADV7344 is not recommended.
It is recommended that the ADV7344 be placed as close as
possible to the output connector, with the DAC output traces as
short as possible.
The termination resistors on the DAC output traces should be
placed as close as possible to and on the same side of the PCB as
the ADV7344. The termination resistors should overlay the
PCB ground plane.
External filter and buffer components connected to the DAC
outputs should be placed as close as possible to the ADV7344 to
minimize the possibility of noise pickup from neighboring
circuitry, and to minimize the effect of trace capacitance on
output bandwidth. This is particularly important when
operating in low drive mode (R
Power Supplies
It is recommended that a separate regulated supply be provided
for each power domain (V
optimal performance, linear regulators rather than switch mode
regulators should be used. If switch mode regulators must be
used, care must be taken with regard to the quality of the output
voltage in terms of ripple and noise. This is particularly true for
the V
individually connected to the system power supply at a single
point through a suitable filtering device, such as a ferrite bead.
AA
and PV
DD
REF
power domains. Each power supply should be
, and R
SET
AA
, V
pins should be placed as close as
DD
SET
, V
= 4.12 kΩ, R
DD_IO
, and PV
L
= 300 Ω).
DD
). For